Analysis On Large-strain Non-linear Consolidation Of Layered Soils And Experimental Study Considering Non-Darcian Flow

The seepage in soft clay doesn't conform to Darcy's flow law and the influences of large-strain assumption on the consolidation of soil have been gradually recognized.However,both considering different forms of non-Darcian flow and large-strain assumption of layered soft clayey soils nonlinear consolidation theory is rarely reported.In this paper,based on the one-dimensional nonlinear consolidation of soft clay considering the threshold hydraulic gradient and Hansbo flow law of seepage,considering different types of non-Darcian flow large-strain one-dimensional nonlinear consolidation of layered soft clayey soils is analyzed in detail and successively governing the model equation and finite difference method.Based on the reliability of numerical solutions,in large-strain conditions study different parameters have effects on considering non-Darcian flow law consolidation of layered soft clayey soils on consolidation behaviors in detail,emphatically investigated comparing the differences in consolidation behaviors of layered soils with small-strain conditions.The research of this paper includes five parts:(1)Permeability and consolidation experiment on the field of soft clay in Lianyungang city,deducing permeability formula of Darcian flow,threshold hydraulic gradient and non-Darcian flow to explore the permeability rules.The preliminary results of multiple experiment datum fitting show that phenomenons of seepage in the soft clay deviate Darcy's flow law and similar with threshold hydraulic gradient and Hansbo seepage law.Finally,assuming the seepage in soft clay follows threshold hydraulic gradient or Hansbo seepage model,determining threshold hydraulic gradient or Hansbo seepage model parameters and seepage velocities expression formulas.(2)Permeability and consolidation experiment proves the seepage in soft clay may correspond to threshold hydraulic gradient or Hansbo flow law.So governing equation of large-strain one-dimensional nonlinear consolidation of soft clay,and using finite difference method to obtain numerical solutions.Comparing with the semi-analytical solutions of large-strain one-dimensional nonlinear consolidation of soft clay under Darcy's law,the reliability of numerical solutions for the proposed consolidation model was verified.Finally,the influences of the threshold hydraulic gradient i0,compression index cc,time-dependent loading qu on large-strain one-dimensional nonlinear consolidation behavior of soil clay was analyzed in detail.(3)It is very necessary to govern equation of large-strain one-dimensional nonlinear consolidation of double-layer foundation,meanwhile using finite difference method to obtain numerical solutions.Comparing with the large-strain one-dimensional nonlinear consolidation of single-layer's solutions under threshold hydraulic gradient law,the reliability of numerical solutions was verified for the proposed consolidation model.Finally,the influences of the upand down-layer's threshold hydraulic gradient i0,relative thickness and the distribution types of geostatic stress on large-strain one-dimensional nonlinear consolidation behavior of double-layer foundation was analyzed.(4)The preliminary results of experiment show that the seepage in soft clay may correspond to Hansbo flow law.The governing equation of under non-Darcian flow large-strain one-dimensional nonlinear consolidation of double-layer foundation and numerical solutions.Comparing with the large-strain one-dimensional nonlinear consolidation of single-layer's solutions under non-Darcy's law,the reliability of numerical solutions for the proposed consolidation model was verified.Finally,the influences of up-and down-layer's the parameter m and i1,rate of time-dependent loading,the final value of external loading qu on large-strain one-dimensional nonlinear consolidation behavior of double-layer foundation was analyzed in detail.(5)To more close to reflect the actual engineering situations.So the governing equation of considering non-Darcian flow and large-strain one-dimensional consolidation of layered soils foundation developed,and using finite difference method to solve governing equation.Comparing with the single-and double-layer foundation solutions of large-strain one-dimensional nonlinear consolidation under non-Darcy's law,the finite difference method for the proposed consolidation model was verified.Finally,by a calculation case of treble-layered soils to analyze consolidation behavior of large-strain one-dimensional nonlinear consolidation of layered soils considering non-Darcian flow,relationship curves of pore pressure vs the depth of the foundation,the settlement of the foundation with time factor and the two different definitions consolidation degree with time factor were described.